Dynamic Web Service Composition System Design, Support Qos

Currently, web services are growing at an explosive speed and many competitive services that can perform the same or similar functions can be easily found as well. As more services can be chosen, users do not only concern about the functional requirements but also the non-functional requirements, such as service price, execution time, availability and executition reliability. Therefore, how to select proper web services in dynamic composition as to satisfy the non-functional restriction from users becomes a critical problem. To deal with this problem, the research can be carried out in the following aspects.Firstly, coordination technology and current web service technology specifications, such as WSDL, UDDI and SOAP, are analyzed. The related theories and technologies in the areas of semantic web are discussed in details.Secondly, in order to make web services to be computer interpretable entities, semantic is applied to web service, OWL-S is extended to support QoS(Quality of Service), service grounding is realized by WSDL and SOAP, and semantic is supplemented for UDDI. The integration of semantic web service which supports QoS is achieved. The storage of register information of web services are classified, which the separation of functional restraints, non-functional restraints and relationships of services can be realized.Thirdly, the five non-functional restrictions, execution price, execution duration, reliability, availability, reputation, from the QoS model of web service are described and defined. The sources of the five non-functional restrictions are discussed. Then based on the model, an optimal algorithm is given.Finally, a system supporting QoS and dynamic service composition is designed for dealing with web service dynamicity and the change of application constraints on Internet. The application system on the basis of web service can be abstractly classified into three different categories of entities, coordinators, roles and web services. QWSRC framework and the function of crucial modules are fully described, meanwhile, the dynamic binding and optimal choice of services are introduced in details. Thus, the dynamicity in service composition process is realized and the non-functional requirements from users are satisfied.